Preliminary GOES Calibrations
Janet Machol NOAA National Geophysical Data Center University of Colorado CIRES Rodney Viereck NOAA Space Weather Prediction Center
Inter-Calibration and Degradation Workshop Belgium Solar-Terrestrial Center of Excellence 15 – 18 April 2013
GOES EUVS Sensors
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GOES: Geostationary Operational Environmental Satellite current GOES XRS 2 x-ray bands: A 0.05-0.4 nm, B 0.1-0.8 nm, since 1972 NOP→13-15 SXI x-ray imager, 3 channels: 0.6-6 nm
EUVS 5 EUV bands, 5-127 nm
GOES-13 2006 GOES-14 2009 GOES-15 2010 Requirements: 30-s sample rate, 30-s latency, 20% uncertainty Actual: 10 s 3 s 15%
GOES EUVS
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GOES EUVS (Panametrics → ATC) • transmission grating spectrographs
• shared gratings for A&B, C&D • detector: silicon photodiodes (IRD) • thin film filters on detector for A-D • no moving parts
• Calibrations at the NRL Beam Line at Brookhaven (John Seeley)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 1401
10
100
1000
10000
100000
1000000
1E7
EUVEEUVD
EUVC
EUVB
EUVA
Instru
ment
Resp
onse
Wavelength (nm)
-200-180-160-140-120-100-80-60-40-20020406080100120
Atmospheric Heating Rate
Heati
ng R
ate(de
g/hr)
wavelength (nm) 0 20 40 60 80 100 120
planned
actual
Earlier GOES EUVS Calibra2ons
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GOES-13: Solar Phys (2010), Evans, Strickland, Woo, McMullin, Plunkett, Viereck, Hill, Woods, and Eparvier Looked at post-launch test period in 2006 (X9 flare). Compared with TIMED SEE and SOHO SEM. All five channels within specified uncertainties
GOES EUVS TIMED SEE SOHO SEM
15%
15%
15%
15%
15%
GOES EUVS Calibra2ons
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How good are the GOES bands? Focus on channels A, B, and E Long term comparisons • daily averages • EVE V3 L3, SOHO SEM • corrected to 1 AU Flare (9 August 2011) • 1-min data
wavelength (nm) 0 20 40 60 80 100 120
A B E
GOES EUVS Calibra2ons
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The irradiance measured in a channel is J [W/m2] = ((Counts - Offset [counts]) * Gain [A/count] –VisibleLightContamination [A]) / ConversionFactor [A/(W/m2)] Offset, Gain, and VisibleLightContamination are determined before launch. ConversionFactor is a function of wavelength and bandpass and requires an assumed spectrum and response function. (Current conversion assumes boxcar response.) We assume the quiet Sun NRL spectrum and calculate Jtot [W/m2] = ∑Ji total irradiance of detector band for NRL model Jsubset [W/m2] = ∑Ji total irradiance of subset of band for NRL model Itot [A] = ∑Ri ·Ji total current of band= detector response x irradiance Jmeas = (Jtot / Itot) · Imeas measured irradiance in full channel Jmeas_subset = (Jsubset / Jtot) · Jmeas measured irradiance in subset of channel
GOES EUV-‐A Bandpass
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SDO EVE edge
NRL solar spectrum
GOES EUV-‐A Irradiances
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Jul Jan 2012
Jul Jan 2013
Jan 2011
Ratio
Sept 2010 to Dec 2012 Comparing with EVE ‘GOES-A band’ 5-15 nm
GOES EUV-‐A Correla2ons
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Sep 2010 – Dec 2012
GOES EUV-‐B
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Comparisons SDO EVE “GOES-B” (25-34 nm), SOHO SEM (26-34 nm)
304 Å He II
SOHO
GOES EUV-‐B
GOES EUV-‐E (Lyman α, 121 nm)
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115 120 125 130 135
dete
ctor
resp
onse
Irradiance
wavelength [nm]
log scales
LASP WHI quiet sun spectrum
GOES EUV-‐E (Lyman α, 121 nm)
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GOES EUV-E degradation of about 7% per year. -- radiation damage to filter -- need to do a fit
GOES EUV-‐E
14
Sep 2010 – Dec 2012
Jul-Dec 2012
9-‐Aug-‐2011
15
1-minute data See dips from heater E-geocorona impact
Next Genera2on…GOES-‐R EXIS
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EUVS-A, -B, -C
XRS-A, -B
0 0.5 1.0 Wavelength (nm)
• High resolution • Lines representative
of different solar regions
GOES-R launch 2015? EXIS (Extreme ultraviolet and X-ray Irradiance Sensors) designed, built by LASP
GOES-‐R EXIS…Instruments
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EUVS-C
XRS-A, -B
EUVS-B
EUVS-A
Si detectors and Be filters • better SNR and dynamic range reflection grating spectrographs § better degradation tracking with redundant filters and bootstrap technique 115-145 nm
25-31 nm
MG II
0.05-0.8nm
EUV from GOES-‐R EXIS
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5-nm Output Spectrum
0 50 100 150 200 250 300 nm
0 50 100 127 nm
𝐸(𝜆↓5𝑛𝑚 , 𝑡)= 𝐴(𝜆↓5𝑛𝑚 )+ ∑𝑖=1↑10▒𝑗↓𝑖 (𝜆↓5𝑛𝑚 ) 𝑃↓𝑖↑𝑚↓𝑖 (𝑡) + ∑𝑖=1↑10▒𝑘↓𝑖 (𝜆↓5𝑛𝑚 ) 𝑄↓𝑖↑𝑛↓𝑖 (𝑡)
High res. spectra of lines, bands representative of different solar regions. Reconstruct full EUV spectra from sparse measurements…. Assumes spectral features that have the same source regions in the solar atmosphere vary similarly.
Previous studies validate technique (FISM). LASP writing algorithm.
Summary
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GOES-15 Comparisons • daily data, 2010- 2012
• Ch A ±3% relative to EVE in 2012
• Ch B ~3% lower than EVE trend same as SOHO • Ch E 7% degradation / year Future • Characterize XRS channels
• Use XRS to parameterize flare signals between quiet sun and flare spectra
• Calibrate and characterize C,D channels
• Look at GOES-13, GOES-14 (-14 duplicates A, B for angular effects on FOV)
• Put out GOES EUVS data on web.
wavelength (nm) 0 20 40 60 80 100 120
A B E
